The man, aged in his 20s, was airlifted to hospital and suffered leg injuries after the incident which took place on Ffordd Heulog on Sunday night.

North Wales Police have launched an investigation into the cause of the explosion which took place at a terraced house on the street just before 6.30pm.

A police spokesman said: “A man in his 20s is currently being treated after he was airlifted to hospital as a result of the incident. His injuries are not believed to be life threatening.”

A local resident, who asked not to be named, told the Daily Post they heard the explosion: “You could hear the bang from about half a mile away.”

The cause of the explosion has yet to be confirmed and police community support officers stood guard outside the house where the explosion took place.

Fire crew at cottages on Ffordd Heulog, Dolgellau

Dolgellau town councillor Delwyn Evans said the incident had caused shock in the quiet Gwynedd market town.

He said: “You just don’t expect that someone would get injured here as a result of an explosion.

“The first I knew about it was when I heard the ambulance helicopter flying in. I initially thought that someone must have got injured on Cadair Idris but I was shocked when I heard what had happened.”

Cllr Evans, who lives near Ffordd Heulog, said there had been a lot of speculation about what caused the explosion, but it was his understanding that it was “nothing sinister” and may have been caused by fireworks.

He added: “My sympathies go out to the neighbours and the family of the young man.”

He also expressed relief that no-one else was injured after the blast.

The North Wales Fire & Rescue Service and the Welsh Ambulance Service also attended the scene.

A Welsh Ambulance Service spokeswoman said: “We were called at 6.21pm on Sunday, May 4, to an address on Ffordd Heulog, Dolgellau.

“Crew in an emergency ambulance, an ambulance officer and a Wales Air Ambulance attended, and a man in his 20s was airlifted to Ysbyty Gwynedd in Bangor.”